Anal Canal Cancer

• • Account for 1.5% of GI tract cancers

  • Usually long history of perianal complaints

  • Disease may be quite extensive at presentation

  • Associated with chronic anal infection (human papillomavirus)

  • Tumors anatomically found from the upper to lower border of the internal anal sphincter, 6-12 mm above dentate line

  • Referred to as epidermoid carcinoma

Epidemiology

• • Women are at increased risk

  • Homosexual males at greatly increased risk

  • 7/106 men; 9/106 women

  • Increased incidence in males and females practicing anal sex

  • Increased risk with history of anogenital warts; STD; > 10 sexual partners; cervical, vulvar, or vaginal cancer

  • Increased incidence in persons who smoke or who are immunosuppressed (HIV infection and transplantation)

Symptoms and Signs

• • Perianal irritation, may be long-standing

  • Palpable mass, may be indurated

  • Bleeding

  • Itching

  • Tenesmus

Laboratory Findings

• • No specific abnormalities

Imaging Findings

• • CT/MRI: Reveal anal mass

  • Endorectal US: Reveals size and depth of invasion and perianal nodes

• • Tumor of anal margin

  • Hemorrhoids

  • Anal melanoma

  • Perianal/perirectal abscess/fistula

  • Low rectal cancer

Rule Out

• • Extension of low rectal adenocarcinoma

  • Anal melanoma

• • Physical exam with digital rectal exam

  • Assessment for lymphadenopathy (groins)

  • Exam under anesthesia, anoscopy with biopsy

  • Endorectal US to assess size and depth of invasion

  • Chest film, CT to assess for metastatic disease

When to Admit

• • Severe bleeding with hemodynamic compromise

  • Intractable symptoms: itching, pain

• • Chemoradiation is mainstay of therapy

  • Role of surgery limited

  • Overall reported recurrence rates with local excision high

Surgery

Indications

• • Local excision for small, well-differentiated, mobile lesions confined to the submucosa

  • Surgery is largely used as salvage procedure or for recurrent/persistent disease (abdominal perineal resection)

Contraindications

• • Nigro protocol of chemoradiation is first-line therapy

Medications

• • Radiation therapy (XRT): 30 Gray to primary tumor and pelvic and inguinal nodes

  • Mitomycin is given on day 1 of XRT

  • Two 4-day infusions of 5-fluorouracil (5-FU) given on day 1 and day 28 of chemoradiation therapy

  • Cisplatin may be used in place of mitomycin

Treatment Monitoring

• • Follow-up rectal and node exam

Complications

• • Recurrence of disease

  • Metastatic disease

Prognosis

• • Tumor size is best predictor

  • Mobile lesions < 2 cm have cure rates of 80%

  • Tumors > 5 cm associated with 50% mortality

  • Metastatic disease more likely to be present ...